Autor:innen:
Martin Ewald | Humboldt Universität zu Berlin | Germany
Teresa Sebastià | Centre de Ciència i Tecnologia Forestal de Catalunya | Spain
Mercedes Ibanez | Centre de Ciència i Tecnologia Forestal de Catalunya | Spain
Katja Klumpp | French National Institute for Agriculture, Food, and Environment | France
Tomaž Žnidaršič | Agricultural Institute of Slovenia | Slovenia
Branko Lukač | Agricultural Institute of Slovenia | Slovenia
Liliane Ruess | Humboldt Universität zu Berlin | Germany
Stable environments and sustainable food production systems depend also on plant diversity. Plant mixtures have several advantages compared to monocultures in terms of goods and services, e.g. high productivity and quality forage, enhanced yield stability, lower susceptibility to pests and diseases, and reduced greenhouse gas emissions. Moreover, increased soil fertility as well as water and nutrient use efficiency, can positively affect soil biodiversity and function. However, a better understanding under changing climate conditions is still needed in vulnerable regions, like the Mediterranean. This is particularly important as, despite the known benefits of forage mixtures, there is a trend in favour of grass monocultures in all Mediterranean areas. To assign the benefits of plant mixtures on soil biodiversity and processes, we performed three case-studies across a climatic gradient. Experimental fields, sown with different proportions of the most common local forage species of grasses, legumes and forbs, were established in France, Slovenia and Spain. The degrees of diversity ranged from monocultures over 4 and 6 species mixtures up to 9 species mixtures This experimental design will allow the identification of the optimal adaptive mixture proportions under given climatic conditions.
Nematodes were used as indicators to assign the structure and function of the soil food web as well as of soil conditions and plant health. The diversity and density of the nematodes and several ecological indices were determined. The latter comprise the Maturity Index (MI) as measure of ecosystem disturbance, the plant parasite index (PPI) related to crop health, and the Channel Index (CI) providing information about the soil decomposition pathways, i.e. the bacterial and fungal energy and carbon channel. Changes in soil food web structure and function were assigned by the Enrichment Index (EI) and Structure Index (SI) giving information on food web nutrient enrichment and stability, respectively. Furthermore, the metabolic footprint was examined as a measurement of the metabolic activities and the carbon (C) and energy flow along decomposition channels.
Taking together; nematode population dynamics, metabolic footprints and ecological indices, will reveal the benefits of sown forage mixtures for soil and crop health in Mediterranean dry areas prone to climate change.